Images captured by imaging apparatuses such as visible light cameras, infrared cameras, and laser cameras are often subject to noise attributable to such as apparatus itself and external environment, and the noise degrades the image quality. To prevent the image degradation, technologies for reducing noise in an image using convolutional neural networks (CNNs) have been disclosed. In such technologies, CNNs learn, using many natural images to which artificial noise has been added, processing for estimating pre-noise-added images from input images with high accuracy.
However, the conventional technologies have been failed to properly reduce noise included in an image in some cases.